sangchureul ssiseun da-eume pododo gati kkeonaeseo jeomsimeul junbihaesseoyo.

씻은 다음에 means after washing.

It is built like this:

• 씻다 = to wash
• 씻은 = washed / having washed
  
  • this is the adnominal form, used before a noun
• 다음 = next, the following thing
• 다음에 = after that / next

So 씻은 다음에 literally means something like after the washing is done or after having washed.

A very natural English translation is simply after washing the lettuce.

It is 씻은 because it is modifying the noun 다음.

In Korean, when a verb comes before a noun, it usually changes into an adnominal form:

• 씻다 = to wash
• 씻은 다음 = the next thing after washing

So this is not just a plain dictionary-form verb. It is a verb form used to describe 다음.

As for 씻어서:

• 씻어서 can connect actions too, but it has a slightly different feel.
• 씻은 다음에 clearly emphasizes first this happens, then the next thing happens.
• It is more explicit about sequence than -아서/어서.

도 means also, too, or as well.

So 포도도 means:

• grapes too
• also grapes
• the grapes as well

It shows that the speaker did something with grapes in addition to something else already mentioned.

A key point: 도 often replaces another particle.

For example, instead of saying something like 포도를 and then adding also, Korean usually just says:

• 포도도

Here, 포도 is still the object of 꺼내다 (to take out), even though 를 is not written.

Because 도 takes over the particle role in 포도도.

Compare:

• 상추를 씻었어요 = I washed the lettuce.
• 포도도 꺼냈어요 = I took out the grapes too.

In the second part, 도 replaces what would often be 를.

So:

• 상추를 = lettuce + object marker
• 포도도 = grapes + also/too

Even without 를, 포도 is still understood as the object of 꺼내서.

Not necessarily.

같이 can mean:

• together
• along with
• at the same time

In this sentence, it most naturally means something like:

• also together with that
• along with that
• as part of the same preparation

So the sentence is not necessarily saying the speaker was with another person. It more likely means the grapes were taken out along with the lettuce-related prep as part of getting lunch ready.

꺼내서 comes from 꺼내다, which means:

• to take out
• to get out
• to pull out

Here it probably means taking the grapes out of somewhere, such as:

• the refrigerator
• a container
• a cupboard

The -서 connects this action to the next one:

• 포도도 같이 꺼내서 점심을 준비했어요
• I took out the grapes too and prepared lunch

So 꺼내서 is linking the action take out to the final action prepare lunch.

This is very normal in Korean.

Korean often links several actions together in one sentence, and only the final verb carries the main sentence ending such as:

• tense
• politeness level
• finality

Here:

• 씻은 다음에 = after washing
• 꺼내서 = taking out / and then taking out
• 준비했어요 = prepared

The final verb 준비했어요 gives the sentence its polite ending and past-time interpretation.

The earlier parts are just connected action forms, not full sentence endings.

Because the speaker is describing a completed series of actions.

• washed the lettuce
• took out the grapes too
• prepared lunch

So 준비했어요 means prepared in polite speech.

Even though the earlier verbs are not in full past-tense sentence form, the whole sentence is understood as describing completed actions.

Yes, but only slightly.

• 점심을 준비했어요 is more explicit and grammatically full.
• 점심 준비했어요 is more casual and conversational, with the object particle omitted.

Korean often drops particles in everyday speech when the meaning is obvious. But with learners, the full form 점심을 준비했어요 is very helpful because it clearly shows that 점심 is the object of 준비하다.

Yes, but the nuance would change a little.

For example:

• 상추를 씻고 포도도 같이 꺼내서 점심을 준비했어요.
• 상추를 씻어서 포도도 같이 꺼내서 점심을 준비했어요.

Differences:

• -고 simply links actions: and, and then
• -은 다음에 more clearly means after doing X
• -아서/어서 can link actions too, but sometimes it can also suggest reason or method depending on context

So 씻은 다음에 is a good choice when the speaker wants to show a clear sequence:

1. wash the lettuce
2. then take out the grapes too
3. prepare lunch

준비했어요 is in the polite informal style, often called the -어요 style.

It is polite and very common in everyday conversation.

So the sentence sounds natural in many normal situations, such as:

• talking to someone you do not want to sound too casual with
• everyday polite conversation
• speaking to classmates, coworkers, or acquaintances

It is less formal than 준비했습니다, but more polite than 준비했어.